In /nix/store/8w1cwm4n3zb0qzrk6l3macl02xxwplvq-unit-script-nginx-teamclaude-auth-start/bin/nginx-teamclaude-auth-start line 13:
printf 'set $teamclaude_key "%s";\n' "$key" > "$RUNTIME_DIRECTORY/key.conf"
       ^---------------------------^ SC2016 (info): Expressions don't expand in single quotes, use double quotes for that.

For more information:
  https://www.shellcheck.net/wiki/SC2016 -- Expressions don't expand in singl...